Improvement power conversion efficiency in graphene quantum dot by functionalization and heteroatom doping used in solar cell

Abstract

First-principles density functional theory (DFT) was adopted for investigating the influence of adatoms (S, Si, Al) upon the graphene quantum dot functionalized with the carboxyl group (CO2H-GQD) in order to find novel materials due to unique optical (redshift) and electronic (lower bandgap) properties for utilization in quantum dot solar cells (QDSCs). For the sake of examining the alteration in the electronic attributes due to the insertion of adatoms, the bandgaps, the LUMO and the HOMO were examined using the density functional B3LYP and the basis set 6-31G. For the sake of examining the charge separation and electron injection in the un-doped and doped CO2H-GQD, we scrutinized the charge transport, molecular electrostatic potential (MESP) and the binding mechanism. The optical attributes demonstrated a broad spectrum in the visible range favorable towards harvesting solar light. We also investigated the parameters of solar cells such as efficiency (η), short circuit current density (Jsc), fill factor (FF), open circuit voltage (Voc) in order for the sake of examining the use of adatom-doped CO2H-GQD in QDSCs. There was an increase in the efficiency of S-doped, Si-doped, and Al-doped CO2H-GQD. Doping the CO2H-GQD led to the maximum efficiency since electron donating nature was more, thereby injecting more electrons in the surface of TiO2. The results demonstrated that such GQD-based sensitizers can be used effectively in QDSCs.